(E,E)-4-{4-[3-(4-Chloroanilino)-1-hydroxybut-2-enylidene]-3-methyl-5-oxo-4,5-dihydro-1H-pyrazol-1-yl}benzenesulfonamide

The molecule of the title compound, C20H19ClN4O4S, features a central pyrazole ring that possesses a benzene substituent, as well as a conjugated =C—C=C—Cmethyl substituent. The benzene ring is slightly twisted [dihedral angle = 7.7 (2)°] with respect to the five-membered ring; the mean plane of the zigzag =C—C=C—C fragment [torsion angle = 178.0 (4)°] is also slightly twisted [dihedral angle = 10.6 (4)°]. The amine and hydroxy groups form intramolecular hydrogen bonds. The amide group uses one of its H atoms to form a hydrogen bond to the sulfamyl O atom of an inversion-related molecule. Adjacent dimers are further linked by an N—Hamido⋯Npyrazole hydrogen bond to generate a linear chain. The crystal studied is a nonmerohedral twin with a minor twin component of 25.6 (2)%.

The molecule of the title compound, C 20 H 19 ClN 4 O 4 S, features a central pyrazole ring that possesses a benzene substituent, as well as a conjugated C-C C-C methyl substituent. The benzene ring is slightly twisted [dihedral angle = 7.7 (2) ] with respect to the five-membered ring; the mean plane of the zigzag C-C C-C fragment [torsion angle = 178.0 (4) ] is also slightly twisted [dihedral angle = 10.6 (4) ]. The amine and hydroxy groups form intramolecular hydrogen bonds. The amide group uses one of its H atoms to form a hydrogen bond to the sulfamyl O atom of an inversion-related molecule. Adjacent dimers are further linked by an N-H amido Á Á Á N pyrazole hydrogen bond to generate a linear chain. The crystal studied is a nonmerohedral twin with a minor twin component of 25.6 (2)%.

Comment
The compound, 4-acetoacetyl-3-methyl-5-onyl-1-phenylpyrazole rearranges under the influence of acetic acid to form functionalized 4-oxopyrano[2,3-c]pyrazoles (Gelin et al., 1983). The addition of a sulfamido unit to the phenyl ring is expected to improve its biological activity; in the present study, the p-sulfamyl analog is reacted with chloroaniline to yield a new p-sulfamylphenylpyrazole derivative (Scheme I). The C 20 H 19 ClN 4 O 4 S (Fig. 1) features a central pyrazole ring that possesses a benzene substituent as well as a conjugated ═ C-C═C-C methyl substituent. The benzene ring is slightly twisted with respect to the five-membered ring; the mean plane of the zigzag ═ C-C═ C-C fragment is also slightly twisted.
The amino and hydroxy groups are intramolecular hydrogen-bond donors. The amido group uses one of its H atoms to form an hydrogen bond to the sulfamyl O atom of an inversion-related molecule. Adjacent dimers are further linked by an N-H amido ···N pyrazole hydrogen bond to generate a linear chain motif (Table 2, Fig. 2).
The solid that separated from solution was collected and recrystallized from ethanol to yield yellow prismatic crystals.

Refinement
The crystal is a non-merohedral twin with a minor twin domain of 25.6 (2)%. Owing to twinning, the amino, amido and hydroxy H-atoms were generated geometrically.
Carbon-bound H-atoms were placed in calculated positions (C-H 0.95 to 0.98, N-H 0.86, O-H 0.84 Å) and were included in the refinement in the riding model approximation, with U(H) set to 1.2 to 1.5U eq (C,N,O). An sp 2 -type of hybridization was assumed for the amino and hydroxy H atoms, and an sp 3 -type of hybridization for the amido H atoms.